1. Field
The present invention relates to a projector apparatus using LEDs as light source, and to a method of controlling the color fluctuation of the light output from the apparatus.
2. Description of the Related Art
Portable and small electronic apparatuses such as mobile telephones have been proposed, which have a projector function of projecting images.
As is known in the art, the output light of any portable projector apparatus changes in color (hue), resulting from the difference in characteristic between the LEDs that are used as light source.
Japanese Patent Application Publication (KOKAI) No. 2006-93822 (Reference 1) discloses the technique of changing the three elements of white light coming from an LED light source, i.e., a red (R) beam, green (G) beam and blue (B) beam, thereby to adjust the color of the image being projected.
Japanese Patent Application Publication (KOKAI) No. 2006-223588 (Reference 2) discloses the technique of reducing the optical output of the light source when the temperature rises to a prescribed value or beyond after the illumination switch has been turned on.
Japanese Patent Application Publication (KOKAI) No. 2002-64223 (Reference 3) discloses the control technique of increasing the luminance of light-emitting elements, at normal temperature.
Reference 1 indeed teaches that an image is projected to “detect the hue” or to “detect the contrast,” and to photograph the image and compare the characteristic of the image with a reference characteristic. Reference 1, however, does not disclose that the colors (R, G and B) the LEDs of the LED light source may output are predicted before they are actually output.
Reference 2 or Reference 3 does not suggest whether the luminance is set high or normal in accordance with the temperature detected when the LED start emitting light.